The writer and producer, who is also Chief Creative Officer at Archie Comics, also discussed what the biggest challenge of bringing Sabrina onto “Riverdale” might be.

“The one thing that’s tricky is, there will always be a genre, mystery element to this show, but it’s hard to introduce a supernatural element,” he said. “I think there’s a way to introduce Sabrina in a way that’s not supernatural, but she is, she’s a witch.”

Aguirre-Sacasa previously described a potential “Sabrina the Teenage Witch” series in the “Riverdale” universe as dark and in the vein of “Rosemary’s Baby.” In other words, nothing like the late ’90s sitcom starring Melissa Joan Hart. (The show aired from 1996 to 2003.)

“As dark as ‘Riverdale’ is, the vision for Sabrina is even darker,” he elaborated. “Riverdale is on one side of the Sweetwater River and Greendale, where Sabrina lives, is on the other. There’s sort of that mythic idea that on one side of the river there’s one reality and on the other side of the river there’s another reality. So who knows? But yeah, there’s definitely a universe where Sabrina pops up in Riverdale, or there’s a version of Sabrina that exists in her own witchy bubble.”

“Riverdale” airs Thursdays at 9 p.m. ET on The CW.

Evolution of Archie, From 1940s Comics to CW's 'Riverdale' (Photos)

Archie Andrews is making his TV debut on the CW's "Riverdale," but those who've grown up with the iconic character from the comics will barely recognize him.

Archie Andrews made his comic book debut in 1941, drawn by artist Bob Montana. The character's iconic design remained largely unchanged for more than 70 years.

Archie Comics

After Jon Goldwater, CEO of Archie Comics and the son of the character's original creator, took control of the company, he made the shocking decision to kill off the character in 2014. The following year, the entire franchise was rebooted with a more modern look drawn by artist Fiona Staples.

Archie Comics

New Zealand actor K. J. Apa is the newest face of the red-headed teen in The CW's "Riverdale," from Archie Comics' Roberto Aguirre-Sacasa and executive producer Greg Berlanti.